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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

Spencer’s claim to the contrary was a result of failing to understand the consensus research he referenced. In The Wall Street Journal this week, Spencer and Bast continued that tradition of misunderstanding and misrepresenting the scientific literature on the expert global warming consensus.

For example, in order to reject the findings of the paper my colleagues and I published last year finding a 97% consensus on human-caused global warming in the peer-reviewed literature, Bast and Spencer referenced a critical comment subsequently published by David Legates et al. in an obscure off-topic journal called Science and Education. That paper was based on a blog post written by Christopher Monckton, who's infamous for calling environmental activists “Hitler Youth.”

Monckton's blog post and paper tried to deny the consensus by ignoring 98% of the papers that endorse it. He compared only papers that explicitly quantified the human contribution to global warming to the full sample of all peer-reviewed papers that mention the phrases “global warming” or “global climate change.”

By that standard, there’s less than a 1% expert consensus on evolution, germ theory, and heliocentric theory, because there are hardly any papers in those scientific fields that bother to say something so obvious as, for example, “the Earth revolves around the sun.” The same is true of human-caused global warming. That Bast and Spencer refer to Monckton and Legates’ fundamentally wrong paper in an obscure off-topic journal as “more reliable research” reveals their bias in only considering denial “reliable.”

Bast and Spencer didn’t just limit their misrepresentations to our paper; they spread the wealth to all of the big global warming consensus studies. The first was done by Naomi Oreskes and published in Science in 2004, finding that in a sample of 928 peer-reviewed climate research abstracts, none rejected human-caused global warming. Bast and Spencer claimed, “scores of articles by prominent [contrarian] scientists … who question the consensus, were excluded.”

This is inaccurate; their ‘skeptical’ papers simply weren’t represented in Oreskes’ sample of 928 papers, which isn’t surprising since these contrarian papers account for less than 3% of the peer-reviewed global warming research. Oreskes’ sample also didn’t capture tens of thousands of other climate papers that are consistent with the 97% consensus. That’s why it’s called a sample.

Bast and Spencer also argued that abstracts don’t necessarily accurately reflect the content of a complete scientific paper, which could be a weakness in Oreskes’ study, given that she only considered the abstracts. However, our study last year included ratings of over 2,000 full papers by the scientist authors themselves. The result? Once again, a 97% consensus on human-caused global warming.

Next came a survey of Earth scientists by Doran & Zimmerman in 2009, and a survey of public statements made by climate researchers by Anderegg and colleagues in 2010, both again finding a 97% consensus on human-caused global warming among climate experts. In their opinion article, Bast and Spencer tried to reject these studies as having relatively small sample sizes.

However, their results were consistent with those in our study, which had a much larger sample size. We found 10,356 scientists whose published climate research has stated a position on human-caused global warming. Among those 10,356 scientists, 98.4% endorsed the consensus. In addition to these consensus studies, at least 80 National Academies of Science and dozens of scientific organizations from around the world agree with the consensus; none oppose it.

Instead of accepting these consistent results that have been published in prestigious peer-reviewed journals like Science, the Proceedings of the National Academy of Sciences, and Environmental Research Letters, Spencer and Bast choose to believe some less robust data that they find more convenient.

Bast and Spencer also tried to downplay the expert consensus, arguing that climate scientists don’t specify that global warming is “dangerous.” What we each consider dangerous is subjective and not scientific – some people think that driving 100 miles per hour in a rain storm isn’t dangerous. However, if the 97% expert consensus is right, it means we’re in for several more degrees of global warming if we continue on a business-as-usual path.

Anything that references the Oregon Petition, which claims that 31,000 scientists deny AGW can safely be dismissed as a load of old tosh. As you say, anyone with a college degree can sign the petition. Still, 31,000 sounds a lot until you realise that around a quarter of the US adult population have college degrees. Taking a fairly conservative estimate of 40 million potential signatories since 1998, we get 31,000 / 40,000,000 = 0.0775%. So the 31,000 scientists deny AGW claim is more accurately stated as fewer than 0.0775% of US college graduates since 1998 can be bothered to sign a petition denying AGW, which doesn't sound quite so impressive.

Regarding the 97% consensus, I reckon that here in the UK it's closer to 100%. I can't actually think of a British climate scientist who is a sceptic. Which is why we often end up with someone like Nigel Lawson in the media arguing the sceptic case.

Wow, where to begin. Firsly, it is unseemly to attack people who disagree with you with terms like "denier". Criticism is central to scientific progress. You never know, you might actually improve your methodology if you listen rationally to criticism. Calling them "denier" and talking about irrelevent facts about their history and rupert murdoch is at best "post-modern" and at worst a cynical attempt to evade the criticism.

"By that standard, there’s less than a 1% expert consensus on evolution, germ theory, and heliocentric theory, because there are hardly any papers in those scientific fields that bother to say something so obvious as, for example, “the Earth revolves around the sun.” The same is true of human-caused global warming."

Are you seriously suggesting that the the earth's climate is as well understood as the heliocentric theory or evolution? Have you heard of scientific fallabalism? It goes like this. A new theory is always assumed to be wrong. This is the default position. Based on this quote the author is so sure that anthropogenic global warming is true that he thinks it's as obvious as the fact that the earth goes around the sun. If all scientists thought this way they would never be able to correct their mistakes and they would hold on to theories no matter what data comes in.

"if the 97% expert consensus is right, it means we’re in for several more degrees of global warming if we continue on a business-as-usual path." This is false. The consensus quoted in your paper said nothing about how much the world will warm in the next century. In fact the criteria did not require any quantification of the amount of warming in the future or in deed in the past 150 years. Accordingly, one could rightly claim to belong to your consensus and still predict relatively little warming over the next century. And then there is the issue of dangerousness. You are right to say that some people are more risk-averse than others. But does this mean that highly risk-averse people should be able to force those who are not so risk averse to pay more for energy? Should wealthy risk-averse westerners be allowed to force poverty-stricken Indians and Chinese not to have access to cheap coal that could allow them access to clean water and clean air and a good life?

"Based on this quote the author is so sure that anthropogenic global warming is true that he thinks it's as obvious as the fact that the earth goes around the sun."

That CO2 is a Greenhouse Gas and warms the planet is as certain as the earth's goes round the sun. And this physical truth of global warming has gone through the progression from hypothesis, to theory, to accepted common knowledge, with all the trials and tribulations of peer review with several counter theories and arguments put against it over some 150years or so.

That this warming is amplified by the earth's internal systems (the climate sensitivity) has also gone through the same rigorous progression.

The uncertainty is how much the earth's internal system amplify the warming and consensus on an exact figure for this is hard to find, for 2 reasons, there are uncertainties in the measurements (like all measurements) and the system is complex and behaves chaotically, meaning that the climate sensitivity is dependent on the initial conditions of the system, in this the earth's continental arrangement, amount of sea ice present, amount of oceanic ice, amount of O2 etc, over geological time and thus is a moving target overall. Being in a time when there is large oceanic ice cover to melt away quickly is suggestive that this might be a time of higher CS than at others. As climate being dangerous, well as in the previous article this week, when CO2 and SO2 are released in large amounts into the atmosphere life can be dramatically reduced it appears, and although that is open to question, as the evidence mounts it is well into the established theory realm and thus most scientist would agree that global warming induced by burning coal can be quite dangerous I would suspect.

Maybe the authors should put out an scientist e-mail and ask several thousand that question sure they find that most would feel that climate change can be very dangerous to life per se never mind a complex civilization with ~50% of its population and more of its wealth near the ocean edge when sea levels are set to rise.

"Should wealthy risk-averse westerners be allowed to force poverty-stricken Indians and Chinese not to have access to cheap coal that could allow them access to clean water and clean air and a good life?"

Show me where this has been suggested. You could try discussing things seriously instead of jumping into cheap rhetoric. Or do actually believe this from reading misinformation somewhere? In fact the usual suggestion is to let non-Western countries increase FF use while alternatives are slowly brought in while the affluent West very sharply reduce their emissions. That would have been substance of all recent climate conferences.

It would be reasonable to hold alternative opinions to AGW if there was actually some data to support some other idea as opposed to, yes, denialism, and misinformation campaigns. If you really think that this exists by all means present the evidence on an appropriate thread.

"cheap coal that could allow them access to clean water and clean air"

That's rather hysterically funny.

Here's what cheap, clean coal looks like in situ where "they" enjoy it :

With regard to risk aversion, we're all in this car together and (to stretch the metaphor) there are no seatbelts. I for one would rather have a cautious driver at the wheel, "inflicting" risk aversion on me, rather than a reckless fool doing the driving.

Doubtless folks wringing their hands about poverty in the 3rd World have already exhausted their own personal means of correcting that problem, for surely they would not be using such an emotional appeal as a cheap rhetorical expediency.

"Firsly, it is unseemly to attack people who disagree with you with terms like "denier"."

Firstly, despite your complaint, nobody was called a "denier" in either the original post, nor in the three comments that preceded yours. Rather, it was said that certain people deny certain propositions, ie, they claim that those propositions are false. You are so determined to control the terms of the debate that even use of simple verbs to describe the beliefs of others is now not OK with you.

So, here are two simple questions:

1) Do Bast and Spencer claim that there is not a 97% consensus of climate scientists who agree that >50% of recent global warming was caused by anthropogenic factors?

2) If Bast and Spencer do make that claim, why do you react so strongly against the simple description that they deny that claim?

Secondly, despite you concern about how unseemly the missing attack was, you seem unconcerned that Spenser should refer to climate scientists as "Global Warming Nazi's", unconcerned about Bast's use of billboards to draw a connection between AGW and the Unabomber, unconcerned about the frequent accusations that climate scientists are guilty of fraud (scientific, and less frequently) financial, an unconcerned about accusations that people seeking policy action against AGW are routinely accused of desiring genocide by your fellow pseudo-skeptics. Absent evidence the contrary, in the form of links to comments where you have protested such activity by your fellow pseudo-skeptics, I will conclude that your concern for civility is, like that of most of your fellow travellors, one sided and hypocritical.

The simple fact is that concern about the term "AGW denier" does not arise from genuine feelings of offense. They arise from the same desire to win the debate by persuasive definitions that led pseudo-skeptics to call themselves "skeptics". It is an attempt to controll the debate by controlling the language used in the debate. As with Orwell's "Big Brother", it shows a determination to controll the language to limit what can be thought.

"Are you seriously suggesting that the the earth's climate is as well understood as the heliocentric theory or evolution?"

No, they were not. They were denying that a sample of explicit endorsements as a percentage of the entire literature can quantify the level of agreement among scientists with a theory. Such a method applied to any scientific literature would fail, which is why it is necessary to quantify all endorsements (explicit and implicity) as a percentage of all endorsements plus rejections (explicit and implicit).

Your use of a puerile strawman to distract from the logic of the argument is noted.

'"if the 97% expert consensus is right, it means we’re in for several more degrees of global warming if we continue on a business-as-usual path." This is false. The consensus quoted in your paper said nothing about how much the world will warm in the next century.'

Having taken a stand for emperical science in your first determined attempt at distracting (see my prior post), you now forget that emperical study requires following the implications of a theory. An immediate implication of a low climate sensitivity is that it is not responsible for most of the warming over the last fifty years. The anthropogenic forcings are fairly well known, and coupled with a climate sensitivity would not have produced enough warming to account for 50% or more of the recent warming.

Conversely, with moderate or high climate sensitivities, the projectible changes in forcings with BAU will result in a large temperature response in the 21st century.

That you think otherwise merely shows that you do not follow through to the emperical implications of the theories that you support, or in this case reject.

1. Deniers deny. It's a simple, apt, descriptive adjective. And, it's far more apt than "alarmist" as the peer reviewed, scientific literature is remarkably free of alarmism. This can be contrasted to denier blogs stating "the economy will be destroyed" etc. if anything whatever besides business as normal is attempted. All the while ignoring that business as normal carries its own costs which may well "destroy" various parts of various economies, of course.

2. Your explanation of how "science progresses by criticism" starts at the wrong place and comes to wrong conclusions. Heliocentrism did not change the course of the planets in the slightest. What heliocentrism did was allow more accurate, easier calculations. Evolution did not change how genes change over time. What evolution does is provide a nice framework for understanding these changes. There is simply NO _theory_ that is going to come along and suddenly make the Earth cool. What could make the Earth cool is various events and processes that are not presently occurring.

3. You don't "criticize" the fact that an apple falls when you drop it any more than you criticize the position of Mars in the sky. You criticize an explanation of why it drops or where the planet appears in celestial coordinates. And interestingly, physicists have really poor explanations--as opposed to very accurate descriptions--of exactly why that apple falls or planet moves.

4. I suggest people taking real science courses from a real scientific sources really do understand the scientific process and the role of criticism within it.

About 15 million people in the US have science or engineering degrees, excluding social science, according to this census source: http://www.census.gov/prod/2012pubs/acs-18.pdf And since the Oregon petition has been around since 1997, it surely includes a lot of people who were once skeptics but are not now, as well as fake names.

The Oregon Petition also includes the names of people who have passed away. There's no way to ascertain whether someone who signed the petition a decade ago and subsequently died would hold the same opinion today given the amount of scientific evidence that has accumulated over the past decade.

What bothers me is the lack of common sense in the people who argue against global warming. They either hide behind kindergarden reasoning, "we had the coldest winter on record" or contrariantism for the sake of it. CO2 is created added to our atmosphere. As that happens the atomsphere gets warmer. Let's say in the old days most CO2 came from animal farts, decomp and lightening strike forest fires. Well clearly since the industrial revolution, we (humans and our by-product industries) have been contributing a lot more CO2 year after year. If you want to argue that it is to late to stop, or that we will be just fine if oceans rise, great. But why disagree with the obvious?

Kernos - Wikipedia has a list here. You will note a preponderance of non-climate scientists in that list as well as a large no. who have "gone emeritus". Inside that list, I would say only Lindzen, Spenser, Christy, and Chylek have any scientific chops in the field worth considering. I dont think any of these 4 are into denying physics, though some of the "natural causes" arguments push Conservation of Energy pretty hard. I also do not think that they have published hypotheses that have not been discredited in the published literature. Corrections welcome.

Of the two or three percent of climate scientists that don't "believe" in man made global warming, how many of them don't deny it, but instead just don't think there's enough evidence yet to make the claim? In other words, we always assume that the two of three percent firmly reject man made global warming, but is that really the case? Perhaps the figure is much lower than the already very low two or three percent, that categorically reject manmade global warming. There may be a very high percentage within the two or three percent, that believe we may be behind the warming. Perhaps Skeptical Science should do a post on that.

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Moderator Response:

(Rob P) - See The Consensus Project (TCP) at the top of the page. Those classified as rejections include papers which minimize the role of humans in global warming and therefore ascribe the bulk of warming to other unexplained forces.

Weeeelll , I think we should defer to the expertise of Anthony Watts. Just compare the number of peer reviewed papers he asks his minions to disparage, to the number of peer reviewed papers he asks them to applaud. I am taking bets the ratio is close to 97%.

Rob P. Thank you for your response. I always stress to people that it's a very high bar to meet, to distinguish man made climate change, from natural forcings, and that a significant percent of the 3% or so of scientists who don't think the bar has been met, don't reject the possibility. When you focus on the 3% it has the effect of putting those who deny the science on the defensive. Something they are always trying to get us to do.

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